Taner Kilic, who was held in the western province of Izmir and appeared in court via video link, denied having the app and said he had proved his innocence through documents presented to the court, AFP news agency reports.

Amnesty said two independent forensic analyses of his phone found that there was no trace of the application ever having been on his device.

The group welcomed Mr Kilic’s release, but said it would continue to press for the charges against the 11 activists to be dropped.

They include the director of Amnesty’s Turkey office, Idil Eser, a German and a Swede, who were released last year.

Gauri van Gulik, Amnesty’s Europe director, said: ”These unfounded prosecutions are an attempt to silence critical voices within Turkey but have only served to highlight the importance of human rights and those who dedicate their lives to defending them.”

President Recep Tayyip Erdogan accuses Mr Gulen of being behind the coup attempt – a charge the cleric denies.

More than 40,000 people were arrested and 120,000 sacked or suspended from their jobs in the aftermath of the failed coup. They include police, military personnel, teachers and public servants.